1. Field of the Invention
The present invention relates to an electronic component.
2. Description of the Related Art
In an electronic control unit according to the related art, a casing for accommodating a circuit board is formed integrally with a connector, and a plurality of terminals on the side of the circuit board are connected to a plurality of terminal units on the side of the connector respectively by wire bonding.
FIG. 2 is a cross-sectional view of an electronic control unit according to the related art. FIG. 3 is a perspective view of an essential part of a pad portion of the electronic control unit according to the related art.
Referring to these drawings, a resinous casing 11 is composed of a body portion 13 with its top face having an opening and a cover 14, and accommodates a circuit board 16. A connector 12 is formed integrally with the casing 11. A plurality of terminal units 19, which are provided with lead portions 17 in the shape of a band plate and with pins 18, are embedded in the connector 12 by insert molding. The terminal units 19 are arranged adjacent to one another and at an equal pitch. In this case, the respective lead portions 17 extend parallel to one another along a top face of a pad portion 22 of the casing 11, that is, along a resinous face 22a. Top faces of the lead portions 17, that is, terminal faces 17a are exposed. The pins 18 protrude into a socket 21 for connecting the connector 12 to a cable (not shown). The casing 11, the connector 12 and the circuit board 16 constitute the electronic control unit.
A plurality of terminals (not shown) formed on the circuit board 16 are electrically connected to the terminal units 19 by wire bonding. For this purpose, bonding wires 23 formed of aluminum wires or the like are caused to oscillate at a high frequency with both ends thereof being pressed against terminals of the circuit board 16 and the lead portions 17 by a bonding tool. As a result, pressure welding sections between the bonding wires 23 at one end and the terminals of the circuit board 16 and pressure welding sections between the bonding wires 23 at the other end and the lead portions 17 are cleared of dirt, oxide film and the like. Thus, the ends of the bonding wires 23 are bonded to the terminals of the circuit board 16 and the lead portions 17 respectively.
However, in an attempt to connect the terminals of the circuit board 16 to the terminal units 19 by wire bonding, it is necessary to press the bonding wires 23 at one end against the lead portions 17 with the aid of the bonding tool. In this case, in order to hold the bonding tool in position, images of the respective lead portions 17 are read, and edge portions, corner portions and the like of the read images are recognized. Then positions of the respective lead portions 17 are detected based on the result of recognition.
However, since resin has adhered to the peripheries of the terminal faces 17a, the edge portions, the corner portions and the like of read images of the respective lead portions 17 cannot be recognized precisely.
Also, since the respective lead portions 17 deviate from their proper locations, it is necessary to read positions of all the lead portions 17. Consequently, in addition to the complication of the overall operation, the cost of production of the electronic control unit goes up.
It is an object of the present invention to provide an electronic component which makes it possible to precisely detect positions of respective lead portions and to lower the cost of production of an electronic control unit, by solving the aforementioned problems of the electronic control unit of the related art.